1. Field of the Invention
The present invention relates to a control device for an automatic transmission for a vehicle such as a automobile, and more particularly to a control device for an automatic transmission in a vehicle in which the intake throttle valve is opened in accordance with the stepping-on of the accelerator pedal by way of an electronic throttle opening control device.
2. Description of the Prior Art
In accordance with the recent developments of the so-called computer control of automobiles it has been thought of and actually practiced to control the opening of the intake throttle valve of the engine in accordance with the stepping-on of the accelerator pedal by way of an electronic throttle opening control device instead of the conventional mechanical linkage. By using such an electronic throttle opening control device it is possible to obtain such an advantage that the opening of the intake throttle valve is not simply controlled in accordance with the amount of stepping-on of the accelerator pedal but is controlled in accordance with certain modification of the driver's request for engine output power expressed in the stepping-on amount of the accelerator pedal by various other control parameters with respect to certain operational conditions of the vehicle.
In order to ensure a driving power of the engine enough to guarantee certain drivability of the vehicle in the case where a failure has occurred in an electric part such as motor, electric circuit, sensor or the like in such an electronic throttle opening control device, it has been proposed in Japanese Patent Laying-open Publication 59-122742 to additionally incorporate such a mechanical control device between the accelerator pedal and the throttle valve that guarantees a minimum opening of the throttle valve when the accelerator pedal is stepped on.
However, it would also happen that the throttle opening increases so much that the driving power of the engine increases due to a failure or the like of an electric part in such an electronic throttle opening control device.